Cruise Control: Description and Operation

CRUISE CONTROL SYSTEM-HELLA GR66

CAUTION: Do not engage cruise control when the vehicle is being used in low transfer gears.

Operation
The Cruise Control system consists of electro-mechanical devices, and comprises of the following components.

Electronic Control Unit (ECU)--The Electronic Control Unit is located behind the lower dash panel attached to the underside of the instrument panel. The Microprocessor based ECU evaluates the signals provided by the driver controls, brake pedal switch and the road speed transducer, and activates the vacuum pump in an appropriate manner. The ECU also has a memory function for set speed storage.

Driver Operated Switches--The main cruise control switch is located in the auxiliary switch panel and activates the cruise control system. The steering wheel switches provide set/accelerate and resume/decelerate features. These switches provide the interface between driver and cruise control system.

Brake Pedal Switch--The Brake Pedal Switch is located under the lower dash attached to the brake pedal mounting bracket. The switch provides for fast disengagement of the cruise control system and rapid return of the throttle levers to the idle position when the brake pedal is applied.

Road Speed Transducer--The Road Speed Transducer is fitted between the upper and lower speedometer cables. It is mounted on a bracket located on the left hand chassis side member adjacent to the rear engine mounting. The transducer provides road speed data to the ECU The cruise control system cannot be engaged until the road speed exceeds 28 mph (45 km/h), the system will automatically disengage at a road speed of 26 mph (42 km/h).

Vacuum Pump--The Vacuum Pump is located in the engine compartment attached to the left hand valance. The vacuum pump is energized when the main control panel is operated, and is actuated by the steering wheel and brake pedal switches. The pump provides a vacuum source to the cruise control actuator at the throttle levers. A control valve in the pump provides for steady increase of road speed or rapid purge of the system when the brake pedal is applied.

Actuator--The Actuator is located in the engine compartment and is bolted to the throttle lever bracketry. The actuator provides the servo mechanism link between the cruise control system and throttle linkage and is operated by vacuum from the vacuum pump.